UPDATED: "I'm hopeful but I don't think he will be back," said NBC entertainment chairman Robert Greenblatt.

In a matter of months, The Office is signing off for good with a supersized 60-minute episode -- but it may be without Steve Carell.

"I'm hopeful but I don't think he will be back," said NBC entertainment chairman Robert Greenblatt at the network's Television Critics Association winter press tour Sunday.

"He left in the way that he wanted that character to leave, and I think he and Greg [Daniels] have talked about it and I don't think he'll be back," Greenblatt explained. "There's maybe a little Hail Mary pass on a cameo, but I think the decision is that it'll go out without him rather than compromising his exit."

In August, executive producer Greg Daniels told reporters that the series finale plan does not hinge on an appearance by Carell. "We have ideas for the ending, and obviously if he would participate, we would have a lot of good times. The idea will fly without him if he can't make it," Daniels said at the time.

An exact airdate for the series finale has yet to be finalized.

"If we didn't let it end this year, I don't know if we would have been able to tell the endings for so many characters that I really want to know the endings for," said Daniels last summer.